The invention is concerned with a drive unit, and more particularly concerns a gear drive unit including a worm gear mounted on an axle.
Drive units of this type are, as a rule, designed as "motor drive units", that is, in a single housing on the one hand, is an electric motor, and on the other, a multi-step RPM reducing gear train. Motor drive units of this kind are, for example, employed as positioning means installed for external mirrors on motor vehicles, in particular for external mirrors on trucks. The devices are relatively small and serve only for the transfer of small turning moments.
In a conventional drive unit of this type, a worm gear is rotatably secured on a protruding rod of a first housing part; a drive shaft is mounted concentrically in the second housing part with the interposing of a bearing ring. The remaining parts of the drive between the worm gear and the drive shaft are designed to be principally self centering. Mounting of these conventional units is associated with some expense. Further, the drive unit is subject to wear.